Wayne Bonner, 44, had been to a number of bars with his wife and other relatives when his stepson fell from a wall and on to a towpath.
He tried to lower himself on to the towpath, but slipped and fell into the Rochdale canal. His body was recovered six hours later.
Manchester coroner Nigel Meadows urged council and waterway bosses to help reduce the number of canal deaths.
Mr Meadows, who has presided over four drowning cases in the city centre in recent years, said fencing and warning signs could help prevent tragedies.
He said: "I note the position of this location and the fact there is no signage, fencing or other lifesaving equipment. I am going to report this. I will send letters to British Waterways and to Manchester City Council. I'm expecting a full response within 28 days. I will want to see all the risk assessments that they have done.
"It would be wrong for me to suggest that draconian measures would reduce the number of deaths, but it seems signage, lifesaving equipment, extra lighting and extra fencing would be appropriate. The authorities should consider everything that is necessary for preventing future tragedies.
"What had been a very enjoyable evening led to a tragedy. Obviously there is an issue over drink, but he was not terribly intoxicated. It was an unfortunate combination of consequences."
He recorded a verdict of accidental death.
Mr Bonner, from Horwich, Bolton, had been out with his wife Lesley, 49, stepson Ian Bell and his stepson's partner. Mr Bell, 24, was treated for concussion following the seven-foot fall on to the towpath. He said he still could not remember what happened before the tragedy.
Mrs Bonner said she was further up the street when it happened. She first realised there was a problem when police arrived.
She said: "I heard someone shout that someone was in the water and when I saw the police I knew Ian had fallen in. They brought him up on a spine board and I couldn't see Wayne so I told the police that I couldn't find my husband.
"I went to the hospital and an officer came into the hospital to tell me."
Passerby Dean Ashworth-Brown and friend Sven Darwood saw Mr Bonner splashing in the water, but said they were unable to help him without risking their own safety.
British Waterways and Manchester Council told the coroner they were taking steps to secure the site.
Adrian Brocklehurst, a health and safety officer with the council, said plans were being drawn up for an extra barrier around the canal wall as well as installing extra lighting, distributing rescue ropes and providing rescue training for staff at Canal Street premises.
The coroner demanded a full update on their efforts and said they should assess other open waterways in the city centre.
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